Explosiveness of Mist/Steam/Air or Mist/Gas/Air Mixtures

摘要

The accidental release of a pressurized gas or liquid not only may lead to an explosive gas- or vapour-cloud, but even more may form a mist/gas/air-cloud (hybrid mixture cloud) and so risk analysis is faced with the question, if such hybrid mixtures may give rise to higher flame speeds and consequently higher explosion pressurizes and more severe damages than gas- or vapour-clouds of comparable turbulence and fuel concentration. This question is dealt with by measuring the flame velocities of test mixtures (octanol mist, propan gas and air) in a 1,7 m exp 3 vessel; the turbulence, the concentration of gaseous and liquid fuel and the mean drop size of the liquid phase are investigated as influencing parameters. Concerning the generation of the mist component the results indicate, that explosive mist/air-mixtures of moderate (e.g. atmospheric) turbulence are instable with respect to droplet-coagulation and so - due to the rapid sedimentation of large coagulated droplets - the spreading of explosive mist-air-mixtures under atmospheric turbulence will be rather limited. (ERA citation 09:018624)